arch/arc/include/asm/smp.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   4  */
   5
   6 #ifndef __ASM_ARC_SMP_H
   7 #define __ASM_ARC_SMP_H
   8
   9 #ifdef CONFIG_SMP
  10
  11 #include <linux/types.h>
  12 #include <linux/init.h>
  13 #include <linux/threads.h>
  14
  15 #define raw_smp_processor_id() (current_thread_info()->cpu)
  16
  17 /* including cpumask.h leads to cyclic deps hence this Forward declaration */
  18 struct cpumask;
  19
  20 /*
  21  * APIs provided by arch SMP code to generic code
  22  */
  23 extern void arch_send_call_function_single_ipi(int cpu);
  24 extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
  25
  26 /*
  27  * APIs provided by arch SMP code to rest of arch code
  28  */
  29 extern void __init smp_init_cpus(void);
  30 extern void first_lines_of_secondary(void);
  31 extern const char *arc_platform_smp_cpuinfo(void);
  32
  33 /*
  34  * API expected BY platform smp code (FROM arch smp code)
  35  *
  36  * smp_ipi_irq_setup:
  37  *      Takes @cpu and @hwirq to which the arch-common ISR is hooked up
  38  */
  39 extern int smp_ipi_irq_setup(int cpu, irq_hw_number_t hwirq);
  40
  41 /*
  42  * struct plat_smp_ops  - SMP callbacks provided by platform to ARC SMP
  43  *
  44  * @info:               SoC SMP specific info for /proc/cpuinfo etc
  45  * @init_early_smp:     A SMP specific h/w block can init itself
  46  *                      Could be common across platforms so not covered by
  47  *                      mach_desc->init_early()
  48  * @init_per_cpu:       Called for each core so SMP h/w block driver can do
  49  *                      any needed setup per cpu (e.g. IPI request)
  50  * @cpu_kick:           For Master to kickstart a cpu (optionally at a PC)
  51  * @ipi_send:           To send IPI to a @cpu
  52  * @ips_clear:          To clear IPI received at @irq
  53  */
  54 struct plat_smp_ops {
  55         const char      *info;
  56         void            (*init_early_smp)(void);
  57         void            (*init_per_cpu)(int cpu);
  58         void            (*cpu_kick)(int cpu, unsigned long pc);
  59         void            (*ipi_send)(int cpu);
  60         void            (*ipi_clear)(int irq);
  61 };
  62
  63 /* TBD: stop exporting it for direct population by platform */
  64 extern struct plat_smp_ops  plat_smp_ops;
  65
  66 #else /* CONFIG_SMP */
  67
  68 static inline void smp_init_cpus(void) {}
  69 static inline const char *arc_platform_smp_cpuinfo(void)
  70 {
  71         return "";
  72 }
  73
  74 #endif  /* !CONFIG_SMP */
  75
  76 /*
  77  * ARC700 doesn't support atomic Read-Modify-Write ops.
  78  * Originally Interrupts had to be disabled around code to gaurantee atomicity.
  79  * The LLOCK/SCOND insns allow writing interrupt-hassle-free based atomic ops
  80  * based on retry-if-irq-in-atomic (with hardware assist).
  81  * However despite these, we provide the IRQ disabling variant
  82  *
  83  * (1) These insn were introduced only in 4.10 release. So for older released
  84  *      support needed.
  85  *
  86  * (2) In a SMP setup, the LLOCK/SCOND atomicity across CPUs needs to be
  87  *      gaurantted by the platform (not something which core handles).
  88  *      Assuming a platform won't, SMP Linux needs to use spinlocks + local IRQ
  89  *      disabling for atomicity.
  90  *
  91  *      However exported spinlock API is not usable due to cyclic hdr deps
  92  *      (even after system.h disintegration upstream)
  93  *      asm/bitops.h -> linux/spinlock.h -> linux/preempt.h
  94  *              -> linux/thread_info.h -> linux/bitops.h -> asm/bitops.h
  95  *
  96  *      So the workaround is to use the lowest level arch spinlock API.
  97  *      The exported spinlock API is smart enough to be NOP for !CONFIG_SMP,
  98  *      but same is not true for ARCH backend, hence the need for 2 variants
  99  */
 100 #ifndef CONFIG_ARC_HAS_LLSC
 101
 102 #include <linux/irqflags.h>
 103 #ifdef CONFIG_SMP
 104
 105 #include <asm/spinlock.h>
 106
 107 extern arch_spinlock_t smp_atomic_ops_lock;
 108 extern arch_spinlock_t smp_bitops_lock;
 109
 110 #define atomic_ops_lock(flags)  do {            \
 111         local_irq_save(flags);                  \
 112         arch_spin_lock(&smp_atomic_ops_lock);   \
 113 } while (0)
 114
 115 #define atomic_ops_unlock(flags) do {           \
 116         arch_spin_unlock(&smp_atomic_ops_lock); \
 117         local_irq_restore(flags);               \
 118 } while (0)
 119
 120 #define bitops_lock(flags)      do {            \
 121         local_irq_save(flags);                  \
 122         arch_spin_lock(&smp_bitops_lock);       \
 123 } while (0)
 124
 125 #define bitops_unlock(flags) do {               \
 126         arch_spin_unlock(&smp_bitops_lock);     \
 127         local_irq_restore(flags);               \
 128 } while (0)
 129
 130 #else /* !CONFIG_SMP */
 131
 132 #define atomic_ops_lock(flags)          local_irq_save(flags)
 133 #define atomic_ops_unlock(flags)        local_irq_restore(flags)
 134
 135 #define bitops_lock(flags)              local_irq_save(flags)
 136 #define bitops_unlock(flags)            local_irq_restore(flags)
 137
 138 #endif /* !CONFIG_SMP */
 139
 140 #endif  /* !CONFIG_ARC_HAS_LLSC */
 141
 142 #endif